Heterodyne point diffraction interferometer based on phase shift of low-frequency-difference acousto-optic frequency shifter

Abstract

The invention discloses a heterodyne point diffraction interferometer based on the phase shift of a low-frequency-difference acousto-optic frequency shifter. The heterodyne point diffraction interferometer based on the phase shift of the low-frequency-difference acousto-optic frequency shifter comprises a light beam adjusting unit, a low-frequency-difference phase shifting unit, a point diffraction unit and an area array detector unit. The light beam adjusting unit is used for adjusting output lasers of a laser device into two laser beams with identical powers. The low-frequency-difference phase shifting unit is used for adjusting the frequencies of the two laser beams obtained by the light beam adjusting unit to obtain two laser beams with the output difference frequency being a low difference frequency lower than 100 Hz. The point diffraction unit is used for dividing the lasers adjusted by the low-frequency-difference phase shifting unit into measuring light and reference light so as to generate interference. The area array detector unit is used for collecting the interference. According to the heterodyne point diffraction interferometer based on the phase shift of the low-frequency-difference acousto-optic frequency shifter, heterodyne interference phase shift of the acousto-optic frequency shifter is adopted to effectively avoid that moving parts exist in the interferometer, the measurement accuracy is improved, the anti-interference performance is good, the low-frequency-difference heterodyne interferometer and the area array detector unit carry out consecutive collection, more abundant information can be obtained, phase position can be solved precisely, and noise influences can be avoided.

Description

technical field [0001] The invention relates to the technical field of optical detection, in particular to a heterodyne diffraction interferometer based on a low frequency difference acousto-optic frequency shifter for phase shifting. Background technique [0002] As the key equipment for integrated circuit manufacturing, the development of lithography machine has received significant support. It has initially mastered the processing and testing of deep ultraviolet lithography machine (DUVL) for 45nm processing technology, and is developing the ultra-violet lithography machine (DUVL) for processing technology below 45nm. Preliminary study on the development of ultraviolet lithography machine (EUVL). The high-end optical equipment represented by the EUVL projection exposure system poses great challenges to the processing of optical components and the integration of optical systems. Interferometer is an indispensable core detection equipment for high-precision optical compone...

AI Technical Summary

Problems solved by technology

[0004] However, due to the use of mechanical movement as a phase shifting method, the accuracy is still not high enough, the cost is high, and the development is diffi

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